Last year, I documented my weight and waist loss journey through Intermittent fasting. In a nutshell, I have an eating window and a fasting window in which I do not consume anything except water. It is important what you eat in the eating window and more importantly how you eat it. Remember the goal of intermittent fasting is to lower our insulin levels thereby reversing insulin resistance. The bulk of current diabetes treatment reduces blood glucose levels by increasing insulin. We will talk about the dangers of high insulin in a separate blog. Insulin is secreted, in proportion, to store the glucose in the blood. So, we must keep our blood glucose as low as possible. So, I adopted a low-carb diet. To avoid any spike with this low-carb diet, I came across research done at Cornell University in which the order of how we eat dictates our blood glucose and insulin level for folks who are diabetic [1] and prediabetic[2].
The order boils down to eating our fiber-rich vegetables first. Then we must eat our fat and protein. The last is our carbs. The way I go about it is to have preferably raw or cooked fiber-rich vegetables for appetizers. Meat or lentils/legumes-based dishes for entrees and carbs like boiled rice or wheat dishes for dessert. Fruits contain fructose and are a strict no-no. So is any dish with added sugar as it contains fructose as well. Remember dessert is always optional. It is not a must-have.
Studies were done on pre-diabetics and the tabulated results are represented in the graph [2] above. In order to keep both our insulin and glucose low, we must eat our vegetables first as seen by the green lines. So, what happens in our body when vegetables are eaten first? Our body physiology is such that all food from our stomach moves into our small intestine for absorption through a narrow passage. Here food moves using the First In First Out ( FIFO) method, albeit loosely. The not-so-strict FIFO method ensures that only after our body absorbs the majority of the energy from vegetables, does energy from carbs come into play. Vegetables are rich in fiber. So, our body has to work hard and long to extract glucose from them. Fiber slows down the movement of food from the stomach to the small intestine called gastric emptying. [4].That's we don't see any spike in our blood glucose during the first 30 minutes when we are still eating our meal.
On the other hand, when we eat carbs first, even before we are done eating our meal, there's a spike. The spike is because carbs or starchy foods like rice and bread are very easy to digest. Many of the simple carbs we eat hardly require any chewing and so we eat more carbs quickly. That's the reason why we feel good when we eat carbs. It's the sugar rush as carbs are quickly turned into glucose (sugar) in the absence of fiber. The spike is really bad because similar to gravity, whatever goes up must come down. We can see the spike peaks at the 60th minute and keeps going down. In two hours the blood glucose level is where it was before we ate our meal. But it keeps going down and in 3 hours, it's very low. This is when our body's hormones make us crave for something sweet as we are low in blood sugar. To prevent such a situation, we must let our blood glucose climb up so high in the first place.
So, why don't we see a spike when we eat carbs last? The fiber in vegetables that we ate first reduces the potency of an enzyme that digests starches, thereby reducing the amount of glucose produced [3]. The fiber also makes a viscous fluid reducing the absorption rate of glucose in the small intestine [3]. Folks afflicted with diabetes might take a medication called acarbose/voglibose. Acarbose blocks the same enzyme whose potency is reduced by consuming vegetables first, which is wholesome food.
Similar to fiber, when fat is present in the small intestine, gastric emptying is slowed [4]. Since we eat carbs last, it takes longer for the glucose from carbs to be absorbed by the body. That's why fat comes second after vegetables in the eating order. Since in nature, fat and protein come together, we eat fat and protein before we eat carbs.
The fiber in vegetables and fat that we ate first and second respectively also provides satiety by delaying gastric emptying [3,4]. We will not feel hungry for a longer time as our hunger hormone ghrelin is suppressed for 3 hours or more when eating carbs last as seen by the orange line in the graph below [5]. When we come to carbs as the last item, we don't gorge on them like we would if we ate carbs first and could even help skip them altogether. Remember dessert is optional.
Now that you know the science behind the order, it's entirely up to us to eat in the right order. Let me share how I eat a South Indian lunch as many of the macronutrients are mixed together. I would eat the vegetable poriyal and the vegetables in sambar first as my appetizer. Then I would drink sambar as my entree. Lastly, I would put a small amount of boiled rice, add sambar to it and eat it with vegetable poriyal in the traditional way. I am sure you can come up with your own way of eating while following the right order. Deconstructed sandwiches, anyone?
Sources:
[5] https://diabetesjournals.org/care/article/41/5/e76/36532/Effect-of-Food-Order-on-Ghrelin-Suppression